docs: def find_sanitizer_from_module(module_name, function_name):
          """
          Attempts to find sanitizer function from given module. If the module
          cannot be imported, or function with given name does not exist in it,
          nothing will be returned by this method. Otherwise the found sanitizer
          function will be returned.
  
          :param module_name: Name of the module to import the function from.
          :type module_name: str
  
          :param function_name: Name of the function to look for inside the
                                module.
          :type function_name: str
  
          :return: Sanitizer function found from the module, if it can be
                   imported and it indeed contains function with the given name.
                   Otherwise None will be returned instead.
          :rtype: callback|None
          """
          try:
              module = importlib.import_module(module_name)
          except ImportError:
              return None
  
          # Look for the function inside the module. At this point it could be
          # pretty much anything.
          callback = getattr(module, function_name, None)
  
          # Function does not exist in this module? Give up.
          if callback is None:
              return None
  
          # It's actually callable function? Return it.
          if callable(callback):
              return callback
  
          # Sanitizer seems to be something else than a function. Throw an
          # exception to report such problem.
          raise ConfigurationError("'%s' in '%s' is %s instead of function" % (
              function_name,
              module_name,
              type(callback),
          ))